diff --git a/Bitkit/Services/CurrencyService.swift b/Bitkit/Services/CurrencyService.swift
index 0abbb6ae6..d269614a2 100644
--- a/Bitkit/Services/CurrencyService.swift
+++ b/Bitkit/Services/CurrencyService.swift
@@ -7,7 +7,10 @@ class CurrencyService {
     private let cache = UserDefaults.standard
     private let cacheKey = "cached_fx_rates"
 
-    private init() {}
+    /// Internal rather than private so tests can substitute a service that does not reach the
+    /// network. `CurrencyViewModel.refresh()` writes the rate cache and mirrors the display
+    /// currency into the app group on success, from a task that can outlive a test.
+    init() {}
 
     func fetchLatestRates() async throws -> [FxRate] {
         var lastError: Error?
diff --git a/BitkitTests/ActivityListTest.swift b/BitkitTests/ActivityListTest.swift
index e551e4e44..b3004a3e3 100644
--- a/BitkitTests/ActivityListTest.swift
+++ b/BitkitTests/ActivityListTest.swift
@@ -3,11 +3,17 @@ import BitkitCore
 import XCTest
 
 final class ActivityTests: XCTestCase {
-    let testDbPath = NSTemporaryDirectory()
+    /// Unique per run: `NSTemporaryDirectory()` is shared with every other suite that calls
+    /// `initDb`, and `init_db` creates blocktank.db alongside activity.db, which none of them
+    /// cleaned up.
+    let testDbPath = FileManager.default.temporaryDirectory
+        .appendingPathComponent("ActivityTests-\(UUID().uuidString)", isDirectory: true).path
     let service = CoreService.shared.activity
 
     override func setUp() async throws {
         try await super.setUp()
+        await drainCoreServiceQueue()
+        try FileManager.default.createDirectory(atPath: testDbPath, withIntermediateDirectories: true)
         // Initialize the database before each test
         _ = try initDb(basePath: testDbPath)
         try await Task.sleep(nanoseconds: 1_000_000_000)
@@ -16,13 +22,8 @@ final class ActivityTests: XCTestCase {
     override func tearDown() async throws {
         try await super.tearDown()
 
-        // Clean up the test database directory
-        let fileManager = FileManager.default
-        let dbPath = (testDbPath as NSString).appendingPathComponent("activity.db")
-
-        if fileManager.fileExists(atPath: dbPath) {
-            try fileManager.removeItem(atPath: dbPath)
-        }
+        await repointCoreToAppStorage()
+        try? FileManager.default.removeItem(atPath: testDbPath)
     }
 
     func testInsertAndRetrieveLightningActivity() async throws {
diff --git a/BitkitTests/AddressTypeIntegrationTests.swift b/BitkitTests/AddressTypeIntegrationTests.swift
index db230b79d..bd4665792 100644
--- a/BitkitTests/AddressTypeIntegrationTests.swift
+++ b/BitkitTests/AddressTypeIntegrationTests.swift
@@ -9,6 +9,24 @@ final class AddressTypeIntegrationTests: XCTestCase {
 
     override func setUp() async throws {
         try await super.setUp()
+        // `resetToDefaults()` writes ~30 real keys. The keychain wipe and LDK storage are namespaced
+        // under test; the app's preferences are not, so snapshot the domain and restore it afterwards.
+        snapshotAppDefaultsDomain()
+        // A running node persists address-search indexes as transactions arrive. Teardown blocks run
+        // last-in, first-out, so stopping it here lands before the restore above; `tearDown()` runs
+        // after both and would stop it too late.
+        addTeardownBlock { [settings] in
+            let lightning = await MainActor.run { settings.lightningService }
+            let isRunning = await MainActor.run { lightning.status?.isRunning == true }
+            if isRunning {
+                try? await lightning.stop()
+            }
+        }
+        // Reset here rather than in tearDown. The domain restore only fixes disk, and
+        // `SettingsViewModel.shared`'s `@AppStorage` does not observe it — so without this the cached
+        // `selectedAddressType` carries between tests and `setMonitoring` returns early at its
+        // "same as selected" guard, before the balance check the test means to exercise.
+        await MainActor.run { settings.resetToDefaults() }
         Logger.test("Starting address type integration test setup", context: "AddressTypeIntegrationTests")
         try Keychain.wipeEntireKeychain()
     }
@@ -22,7 +40,6 @@ final class AddressTypeIntegrationTests: XCTestCase {
             try? await lightning.stop()
         }
         try? await lightning.wipeStorage(walletIndex: walletIndex)
-        await MainActor.run { settings.resetToDefaults() }
         try await super.tearDown()
     }
 
diff --git a/BitkitTests/AddressTypeSettingsTests.swift b/BitkitTests/AddressTypeSettingsTests.swift
index 7b1c7cdb4..8f277d276 100644
--- a/BitkitTests/AddressTypeSettingsTests.swift
+++ b/BitkitTests/AddressTypeSettingsTests.swift
@@ -11,14 +11,12 @@ final class AddressTypeSettingsTests: XCTestCase {
 
     override func setUp() {
         super.setUp()
+        // `resetToDefaults()` writes ~30 real keys, including pinEnabled, useBiometrics and
+        // requirePinForPayments; the tests then write address-type keys directly.
+        snapshotAppDefaultsDomain()
         settings.resetToDefaults()
     }
 
-    override func tearDown() {
-        settings.resetToDefaults()
-        super.tearDown()
-    }
-
     // MARK: - SettingsBackupConfig (address type keys)
 
     func testSettingsBackupConfigContainsAddressTypeKeys() {
diff --git a/BitkitTests/AppStateIsolation.swift b/BitkitTests/AppStateIsolation.swift
index 754d8a4a3..592cd2959 100644
--- a/BitkitTests/AppStateIsolation.swift
+++ b/BitkitTests/AppStateIsolation.swift
@@ -1,3 +1,5 @@
+@testable import Bitkit
+import BitkitCore
 import Foundation
 import XCTest
 
@@ -13,6 +15,10 @@ import XCTest
 ///    the app's domain at all.
 /// 2. `snapshotAppDefaults(_:)` when it does not, so the keys are put back afterwards.
 /// 3. `guardAppDefaults(_:)` on suites that should write nothing, to keep it that way.
+///
+/// All three register their work with `addTeardownBlock`, which XCTest runs **before** `tearDown()`.
+/// So a `tearDown` that also clears the same key wins, and silently defeats the restore — if a suite
+/// has one, delete it and let the restore be the cleanup.
 extension XCTestCase {
     /// A `UserDefaults` suite unique to this test, emptied before it runs and removed afterwards.
     func makeIsolatedDefaults(_ label: String = #function, file: StaticString = #filePath, line: UInt = #line) throws -> UserDefaults {
@@ -23,9 +29,27 @@ extension XCTestCase {
         return defaults
     }
 
+    /// Restores the app's entire persistent domain when the test ends. For suites that call
+    /// `SettingsViewModel.resetToDefaults()`, which writes ~30 real keys in one go — including
+    /// `pinEnabled`, `useBiometrics` and `requirePinForPayments` — or that otherwise touch more keys
+    /// than are worth enumerating. Restoring the whole domain also removes keys the test added.
+    func snapshotAppDefaultsDomain(file: StaticString = #filePath, line: UInt = #line) {
+        guard let domain = Bundle.main.bundleIdentifier else {
+            XCTFail("No bundle identifier to snapshot", file: file, line: line)
+            return
+        }
+        let defaults = UserDefaults.standard
+        let snapshot = defaults.persistentDomain(forName: domain) ?? [:]
+        addTeardownBlock { defaults.setPersistentDomain(snapshot, forName: domain) }
+    }
+
     /// Restores `keys` in `UserDefaults.standard` when the test ends, removing any that are absent
     /// now. Use when the code under test has no seam for injected defaults.
     func snapshotAppDefaults(_ keys: String...) {
+        snapshotAppDefaults(keys)
+    }
+
+    func snapshotAppDefaults(_ keys: [String]) {
         let defaults = UserDefaults.standard
         let snapshot = keys.map { (key: $0, value: defaults.object(forKey: $0)) }
         addTeardownBlock {
@@ -39,6 +63,51 @@ extension XCTestCase {
         }
     }
 
+    /// Restores `keys` in the shared `group.bitkit` suite when the test ends. Constructing a
+    /// `CurrencyViewModel` syncs the display currency into that suite from its initializer, so any
+    /// suite that builds one writes state the widget extension reads.
+    func snapshotAppGroupDefaults(_ keys: String...) {
+        guard let defaults = UserDefaults(suiteName: "group.bitkit") else { return }
+        let snapshot = keys.map { (key: $0, value: defaults.object(forKey: $0)) }
+        addTeardownBlock {
+            for entry in snapshot {
+                if let value = entry.value {
+                    defaults.set(value, forKey: entry.key)
+                } else {
+                    defaults.removeObject(forKey: entry.key)
+                }
+            }
+        }
+    }
+
+    /// Waits for work already queued on the core service queue to finish.
+    ///
+    /// `CoreService.init` calls `initDb` against the app's real storage twice — once synchronously and
+    /// once queued — and `initDb` is last-one-wins. Touching `CoreService.shared` and then calling
+    /// `initDb` against a temp directory is therefore not enough on its own: the queued call can land
+    /// afterwards and point the globals back at the app's database. The queue is serial, so enqueueing
+    /// a no-op and awaiting it drains whatever was queued ahead of it.
+    func drainCoreServiceQueue() async {
+        // Both copies: `ServiceQueue` is compiled into the test target as well as the app, so each has
+        // its own `coreQueue`. `CoreService.shared` reached through `Bitkit.` queues onto the app
+        // module's, which the test target's drain would not wait on.
+        _ = try? await ServiceQueue.background(.core) { true }
+        _ = try? await Bitkit.ServiceQueue.background(.core) { true }
+    }
+
+    /// Points bitkit-core's global connections back at the app's own storage, for a suite that moved
+    /// them to a temp directory. Call it before unlinking that directory: the connections stay open on
+    /// the old path, and a later write through core then fails with `attempt to write a readonly
+    /// database`. The app's storage is namespaced under test, so this is a safe target.
+    ///
+    /// `init_db` also rebuilds the Blocktank client with bitkit-core's default URL, which is mainnet
+    /// (`api1.blocktank.to`). Without restoring `Env.blocktankClientServer`, every later suite's
+    /// regtest faucet call 404s.
+    func repointCoreToAppStorage() async {
+        _ = try? initDb(basePath: Env.bitkitCoreStorage(walletIndex: 0).path)
+        try? await updateBlocktankUrl(newUrl: Env.blocktankClientServer)
+    }
+
     /// Skips the test unless `BITKIT_DESTRUCTIVE_TESTS=1` is set. For the handful of suites that
     /// deliberately operate on real, un-namespaceable state — the React-Native migration source under
     /// `~/Documents`, for instance — and so can only run on a simulator that may be erased afterwards.
@@ -79,3 +148,17 @@ extension XCTestCase {
         }
     }
 }
+
+/// A `CurrencyService` that never reaches the network.
+///
+/// `CurrencyViewModel` starts polling from its initializer, and `refresh()` writes `cached_fx_rates`
+/// and mirrors the display currency into the shared app group — but only on success. Failing the
+/// fetch keeps both writes from ever happening, which a snapshot cannot do on its own: the refresh
+/// is unstructured and can complete after the restore has already run.
+final class OfflineCurrencyService: CurrencyService {
+    struct Offline: Error {}
+
+    override func fetchLatestRates() async throws -> [FxRate] {
+        throw Offline()
+    }
+}
diff --git a/BitkitTests/BlocktankRefundAddressLiveIntegrationTests.swift b/BitkitTests/BlocktankRefundAddressLiveIntegrationTests.swift
index ea246d49e..0deb4d7fa 100644
--- a/BitkitTests/BlocktankRefundAddressLiveIntegrationTests.swift
+++ b/BitkitTests/BlocktankRefundAddressLiveIntegrationTests.swift
@@ -11,6 +11,18 @@ final class BlocktankRefundAddressLiveIntegrationTests: XCTestCase {
 
     override func setUp() async throws {
         try await super.setUp()
+        // `resetToDefaults()` in both hooks writes ~30 real keys, and `clear()` drops the user's own
+        // refund address. The keychain wipe and LDK storage are namespaced under test; these are not.
+        snapshotAppDefaultsDomain()
+        // A running node persists address-search indexes as transactions arrive. Teardown blocks run
+        // last-in, first-out, so stopping it here lands before the restore above; `tearDown()` runs
+        // after both and would stop it too late.
+        addTeardownBlock { [lightning] in
+            let isRunning = await MainActor.run { lightning.status?.isRunning == true }
+            if isRunning {
+                try? await lightning.stop()
+            }
+        }
         try Bitkit.Keychain.wipeEntireKeychain()
         Bitkit.SettingsViewModel.shared.resetToDefaults()
         Bitkit.BlocktankRefundAddressStore().clear()
@@ -23,7 +35,6 @@ final class BlocktankRefundAddressLiveIntegrationTests: XCTestCase {
         }
         try? await lightning.wipeStorage(walletIndex: walletIndex)
         try Bitkit.Keychain.wipeEntireKeychain()
-        Bitkit.SettingsViewModel.shared.resetToDefaults()
         try await super.tearDown()
     }
 
diff --git a/BitkitTests/BlocktankRefundAddressProviderTests.swift b/BitkitTests/BlocktankRefundAddressProviderTests.swift
index 9b85995f3..945332c8e 100644
--- a/BitkitTests/BlocktankRefundAddressProviderTests.swift
+++ b/BitkitTests/BlocktankRefundAddressProviderTests.swift
@@ -38,14 +38,12 @@ final class BlocktankRefundAddressProviderTests: XCTestCase {
 
     override func setUp() {
         super.setUp()
+        // `clear()` here and in tearDown, `restoreAppCacheData`, `resetToDefaults()` and the corrupt
+        // cache fixture all write UserDefaults.standard — the host app's own preferences.
+        snapshotAppDefaultsDomain()
         BlocktankRefundAddressStore().clear()
     }
 
-    override func tearDown() {
-        BlocktankRefundAddressStore().clear()
-        super.tearDown()
-    }
-
     private func makeProvider(
         state: State,
         lookup: ((UInt32) async throws -> BlocktankRefundAddress)? = nil,
diff --git a/BitkitTests/BlocktankTests.swift b/BitkitTests/BlocktankTests.swift
index 29a37df5d..ddc71866e 100644
--- a/BitkitTests/BlocktankTests.swift
+++ b/BitkitTests/BlocktankTests.swift
@@ -3,11 +3,17 @@ import BitkitCore
 import XCTest
 
 final class BlocktankTests: XCTestCase {
-    let testDbPath = NSTemporaryDirectory()
+    /// Unique per run: `NSTemporaryDirectory()` is shared with every other suite that calls
+    /// `initDb`, and `init_db` creates blocktank.db alongside activity.db, which none of them
+    /// cleaned up.
+    let testDbPath = FileManager.default.temporaryDirectory
+        .appendingPathComponent("BlocktankTests-\(UUID().uuidString)", isDirectory: true).path
     let service = CoreService.shared.blocktank
 
     override func setUp() async throws {
         try await super.setUp()
+        await drainCoreServiceQueue()
+        try FileManager.default.createDirectory(atPath: testDbPath, withIntermediateDirectories: true)
         // Initialize the database before each test
         _ = try initDb(basePath: testDbPath)
         try await updateBlocktankUrl(newUrl: Env.blocktankClientServer)
@@ -15,6 +21,8 @@ final class BlocktankTests: XCTestCase {
 
     override func tearDown() async throws {
         try await super.tearDown()
+        await repointCoreToAppStorage()
+        try? FileManager.default.removeItem(atPath: testDbPath)
     }
 
     func testGetInfo() async throws {
diff --git a/BitkitTests/ChannelPurchaseFlow.swift b/BitkitTests/ChannelPurchaseFlow.swift
index d100e7663..75eb18bbc 100644
--- a/BitkitTests/ChannelPurchaseFlow.swift
+++ b/BitkitTests/ChannelPurchaseFlow.swift
@@ -3,13 +3,22 @@ import BitkitCore
 import XCTest
 
 final class PaymentFlowTests: XCTestCase {
-    let testDbPath = NSTemporaryDirectory()
     let walletIndex = 0
     let blocktank = CoreService.shared.blocktank
     let lightning = LightningService.shared
 
     override func setUp() async throws {
         try await super.setUp()
+        // `StartupHandler.createNewWallet` resets `selectedAddressType` and `addressTypesToMonitor` for a
+        // new wallet, and the running node persists address-search indexes. Teardown blocks run
+        // last-in, first-out, so the node stop registered below runs before this restore.
+        snapshotAppDefaultsDomain()
+        addTeardownBlock { [lightning] in
+            let isRunning = await MainActor.run { lightning.status?.isRunning == true }
+            if isRunning {
+                try? await lightning.stop()
+            }
+        }
         Logger.test("Starting payment flow test setup", context: "PaymentFlowTests")
 
         // Wipe the keychain before starting tests
diff --git a/BitkitTests/ContactsManagerTests.swift b/BitkitTests/ContactsManagerTests.swift
index 27cc195d1..09ae6b7f1 100644
--- a/BitkitTests/ContactsManagerTests.swift
+++ b/BitkitTests/ContactsManagerTests.swift
@@ -6,14 +6,11 @@ import XCTest
 final class ContactsManagerTests: XCTestCase {
     override func setUp() {
         super.setUp()
+        // tearDown used to delete this outright, so a user who had enabled Paykit UI lost the setting.
+        snapshotAppDefaults(PaykitFeatureFlags.uiEnabledKey)
         UserDefaults.standard.set(false, forKey: PaykitFeatureFlags.uiEnabledKey)
     }
 
-    override func tearDown() {
-        UserDefaults.standard.removeObject(forKey: PaykitFeatureFlags.uiEnabledKey)
-        super.tearDown()
-    }
-
     func testPubkyPublicKeyFormatNormalizesPrefixedAndUnprefixedKeys() {
         let rawKey = "3rsduhcxpw74snwyct86m38c63j3pq8x4ycqikxg64roik8yw5xg"
         let prefixedKey = "pubky\(rawKey)"
diff --git a/BitkitTests/NewsWidgetTitleTests.swift b/BitkitTests/NewsWidgetTitleTests.swift
index 0f9a6bfbf..afa2a9f37 100644
--- a/BitkitTests/NewsWidgetTitleTests.swift
+++ b/BitkitTests/NewsWidgetTitleTests.swift
@@ -10,12 +10,22 @@ import XCTest
 final class NewsWidgetTitleTests: XCTestCase {
     override func setUp() {
         super.setUp()
+        // `savedWidgets` is the user's home-screen layout; these tests delete it and persist
+        // a synthetic set over the top.
+        snapshotAppDefaults("savedWidgets")
+        // Saving a widget also mirrors its options into the shared group.bitkit suite, which the
+        // home-screen widget extension reads.
+        snapshotAppGroupDefaults(
+            "home_screen_news_widget_options_v1",
+            "home_screen_price_widget_options_v1",
+            "home_screen_blocks_widget_options_v1",
+            "home_screen_weather_widget_options_v1"
+        )
         UserDefaults.standard.removeObject(forKey: "savedWidgets")
         NewsViewModel.shared.widgetData = nil
     }
 
     override func tearDown() {
-        UserDefaults.standard.removeObject(forKey: "savedWidgets")
         NewsViewModel.shared.widgetData = nil
         super.tearDown()
     }
diff --git a/BitkitTests/NumberPadTests.swift b/BitkitTests/NumberPadTests.swift
index e3fedcc20..a7187f0a4 100644
--- a/BitkitTests/NumberPadTests.swift
+++ b/BitkitTests/NumberPadTests.swift
@@ -3,6 +3,22 @@ import XCTest
 
 @MainActor
 final class NumberPadTests: XCTestCase {
+    override func setUp() {
+        super.setUp()
+        // Building a `CurrencyViewModel` syncs the display currency into the shared group.bitkit
+        // suite from its initializer, which the widget extension reads. Setting `selectedCurrency`
+        // also re-formats the cached weather widget fee into that currency and rewrites it there.
+        snapshotAppGroupDefaults(
+            "home_screen_display_currency_code_v1",
+            "home_screen_display_currency_symbol_v1",
+            "weather_widget_latest_v1",
+            "weather_widget_latest_timestamp_v1"
+        )
+        // `mockCurrency` sets selectedCurrency and displayUnit, both of which write through to the
+        // app's own preferences — a developer on EUR/classic otherwise ends a run on USD/modern.
+        snapshotAppDefaults("primaryDisplay", "cached_fx_rates", "selectedCurrency", "bitcoinDisplayUnit")
+    }
+
     func testFiatDecimalInput() {
         let viewModel = AmountInputViewModel()
         let currency = mockCurrency(primaryDisplay: .fiat)
@@ -520,7 +536,7 @@ final class NumberPadTests: XCTestCase {
     // MARK: - Helper Methods
 
     private func mockCurrency(primaryDisplay: PrimaryDisplay, displayUnit: BitcoinDisplayUnit = .modern) -> CurrencyViewModel {
-        let currency = CurrencyViewModel()
+        let currency = CurrencyViewModel(currencyService: OfflineCurrencyService())
         currency.primaryDisplay = primaryDisplay
         currency.selectedCurrency = "USD"
         currency.displayUnit = displayUnit
diff --git a/BitkitTests/PaymentNavigationHelperTests.swift b/BitkitTests/PaymentNavigationHelperTests.swift
index b304b7f05..0a2ac2110 100644
--- a/BitkitTests/PaymentNavigationHelperTests.swift
+++ b/BitkitTests/PaymentNavigationHelperTests.swift
@@ -6,24 +6,28 @@ import XCTest
 @MainActor
 final class PaymentNavigationHelperTests: XCTestCase {
     private let settings = SettingsViewModel.shared
-    private var originalEnableQuickpay = false
-    private var originalQuickpayAmount: Double = 0
-    private var originalQuickpayDailyLimitMultiplier: Double = 0
-    private var originalPinEnabled = false
-    private var originalRequirePinForPayments = false
-    private var originalCachedRates: Data?
     private var spendDefaults: UserDefaults!
     private var spendSuiteName: String!
     private var spendStore: QuickPaySpendStore!
 
     override func setUp() {
         super.setUp()
-        originalEnableQuickpay = settings.enableQuickpay
-        originalQuickpayAmount = settings.quickpayAmount
-        originalQuickpayDailyLimitMultiplier = settings.quickpayDailyLimitMultiplier
-        originalPinEnabled = settings.pinEnabled
-        originalRequirePinForPayments = settings.requirePinForPayments
-        originalCachedRates = UserDefaults.standard.data(forKey: "cached_fx_rates")
+        // Building a `CurrencyViewModel` syncs the display currency into the shared group.bitkit
+        // suite from its initializer, which the widget extension reads.
+        snapshotAppGroupDefaults("home_screen_display_currency_code_v1", "home_screen_display_currency_symbol_v1")
+        // Snapshot from disk, not from `SettingsViewModel.shared`. Its `@AppStorage` properties do not
+        // observe `setPersistentDomain`, so after an earlier suite's `resetToDefaults()` the singleton
+        // still reports the defaults — capturing those as "originals" and writing them back in
+        // tearDown overwrote the user's values that the domain restore had just put back.
+        snapshotAppDefaults(
+            "primaryDisplay",
+            "cached_fx_rates",
+            "enableQuickpay",
+            "quickpayAmount",
+            "quickpayDailyLimitMultiplier",
+            "pinEnabled",
+            "requirePinForPayments"
+        )
 
         spendSuiteName = "PaymentNavigationHelperTests.\(UUID().uuidString)"
         spendDefaults = UserDefaults(suiteName: spendSuiteName)
@@ -40,18 +44,8 @@ final class PaymentNavigationHelperTests: XCTestCase {
     }
 
     override func tearDown() {
-        settings.enableQuickpay = originalEnableQuickpay
-        settings.quickpayAmount = originalQuickpayAmount
-        settings.quickpayDailyLimitMultiplier = originalQuickpayDailyLimitMultiplier
-        settings.pinEnabled = originalPinEnabled
-        settings.requirePinForPayments = originalRequirePinForPayments
-
-        if let originalCachedRates {
-            UserDefaults.standard.set(originalCachedRates, forKey: "cached_fx_rates")
-        } else {
-            UserDefaults.standard.removeObject(forKey: "cached_fx_rates")
-        }
-
+        // No settings restored here: teardown blocks run before this, so writing the singleton's
+        // values back would land on top of the snapshot's restore.
         spendDefaults.removePersistentDomain(forName: spendSuiteName)
         spendDefaults = nil
         spendStore = nil
@@ -70,7 +64,7 @@ final class PaymentNavigationHelperTests: XCTestCase {
     }
 
     func testSkipsQuickpayWhenDailySpendCapIsExceeded() throws {
-        let rates = QuickPaySpendRates.live(CurrencyViewModel())
+        let rates = QuickPaySpendRates.live(CurrencyViewModel(currencyService: OfflineCurrencyService()))
         for i in 0 ..< 5 {
             XCTAssertNotNil(
                 try spendStore.reserveBound(
@@ -87,7 +81,7 @@ final class PaymentNavigationHelperTests: XCTestCase {
     }
 
     func testAllowsQuickpayWhenSpendPlusAmountEqualsDailyCap() throws {
-        let rates = QuickPaySpendRates.live(CurrencyViewModel())
+        let rates = QuickPaySpendRates.live(CurrencyViewModel(currencyService: OfflineCurrencyService()))
         for i in 0 ..< 4 {
             XCTAssertNotNil(try spendStore.reserveBound(paymentHash: "under\(i)", amountSats: 5000, thresholdUsd: 5, multiplier: 5, rates: rates))
         }
@@ -105,7 +99,7 @@ final class PaymentNavigationHelperTests: XCTestCase {
                 amountSats: 1000,
                 thresholdUsd: 5,
                 multiplier: 5,
-                rates: QuickPaySpendRates.live(CurrencyViewModel())
+                rates: QuickPaySpendRates.live(CurrencyViewModel(currencyService: OfflineCurrencyService()))
             )
         )
         let coordinator = QuickPayPaymentCoordinator(store: spendStore, sendBolt11: { _ in hash }, listRows: { [] })
@@ -115,7 +109,7 @@ final class PaymentNavigationHelperTests: XCTestCase {
 
     func testUsesQuickpayWhenHashIsOpenEvenIfDailyCapIsExceeded() throws {
         settings.quickpayDailyLimitMultiplier = 1
-        let rates = QuickPaySpendRates.live(CurrencyViewModel())
+        let rates = QuickPaySpendRates.live(CurrencyViewModel(currencyService: OfflineCurrencyService()))
         let hash = "aabbccdd"
         XCTAssertNotNil(try spendStore.reserveBound(paymentHash: hash, amountSats: 1000, thresholdUsd: 5, multiplier: 1, rates: rates))
         XCTAssertNotNil(try spendStore.reserveBound(paymentHash: "cap0", amountSats: 4000, thresholdUsd: 5, multiplier: 1, rates: rates))
@@ -132,7 +126,7 @@ final class PaymentNavigationHelperTests: XCTestCase {
                 amountSats: 1000,
                 thresholdUsd: 5,
                 multiplier: 5,
-                rates: QuickPaySpendRates.live(CurrencyViewModel())
+                rates: QuickPaySpendRates.live(CurrencyViewModel(currencyService: OfflineCurrencyService()))
             )
         )
         let coordinator = QuickPayPaymentCoordinator(store: spendStore, sendBolt11: { _ in hash }, listRows: { [] })
@@ -141,7 +135,7 @@ final class PaymentNavigationHelperTests: XCTestCase {
         XCTAssertEqual(
             PaymentNavigationHelper.contactPaymentRoute(
                 app: app,
-                currency: CurrencyViewModel(),
+                currency: CurrencyViewModel(currencyService: OfflineCurrencyService()),
                 settings: settings,
                 spendStore: spendStore,
                 coordinator: coordinator
@@ -209,7 +203,7 @@ final class PaymentNavigationHelperTests: XCTestCase {
     private func sendRoute(for app: AppViewModel, coordinator: QuickPayPaymentCoordinator? = nil) -> SendRoute? {
         PaymentNavigationHelper.appropriateSendRoute(
             app: app,
-            currency: CurrencyViewModel(),
+            currency: CurrencyViewModel(currencyService: OfflineCurrencyService()),
             settings: settings,
             spendStore: spendStore,
             coordinator: coordinator
@@ -219,7 +213,7 @@ final class PaymentNavigationHelperTests: XCTestCase {
     private func contactPaymentRoute(for app: AppViewModel) -> SendRoute? {
         PaymentNavigationHelper.contactPaymentRoute(
             app: app,
-            currency: CurrencyViewModel(),
+            currency: CurrencyViewModel(currencyService: OfflineCurrencyService()),
             settings: settings,
             spendStore: spendStore
         )
diff --git a/BitkitTests/PrivatePaykitServiceTests.swift b/BitkitTests/PrivatePaykitServiceTests.swift
index dcb92cf69..618b4b290 100644
--- a/BitkitTests/PrivatePaykitServiceTests.swift
+++ b/BitkitTests/PrivatePaykitServiceTests.swift
@@ -3,6 +3,15 @@ import Paykit
 import XCTest
 
 final class PrivatePaykitServiceTests: XCTestCase {
+    override func setUp() {
+        super.setUp()
+        // Constructing `PrivatePaykitService` and mutating it writes the real cache state, injecting
+        // fake contacts and invoices into the user's own and flagging the wallet backup dirty. It also
+        // reaches `PrivatePaykitAddressReservationStore`, which persists its own ledger and removes the
+        // receive address outright — more keys than are worth enumerating, so snapshot the domain.
+        snapshotAppDefaultsDomain()
+    }
+
     func testSupportedReceiverPathsPreserveSupportedOrderWhenMergingDiscoveredServerPath() async {
         let service = PrivatePaykitService()
 
diff --git a/BitkitTests/PubkyImageCacheTests.swift b/BitkitTests/PubkyImageCacheTests.swift
index d8a61a5ab..2ec3fa4fb 100644
--- a/BitkitTests/PubkyImageCacheTests.swift
+++ b/BitkitTests/PubkyImageCacheTests.swift
@@ -5,14 +5,18 @@ import XCTest
 
 final class PubkyImageCacheTests: XCTestCase {
     func testClearRemovesCachedImageFromMemoryAndDisk() async throws {
-        let cache = PubkyImageCache.shared
+        // `.shared` writes to the real ~/Library/Caches/pubky-images, so clearing it here threw away
+        // the user's downloaded avatars. Every other test in this file already injects a directory.
+        let directory = try temporaryDirectory()
+        defer { try? FileManager.default.removeItem(at: directory) }
+        let cache = PubkyImageCache(diskDirectory: directory)
         let uri = "pubky://test-user/pub/bitkit.to/blobs/avatar.jpg"
         let image = UIGraphicsImageRenderer(size: CGSize(width: 1, height: 1)).image { context in
             context.cgContext.setFillColor(UIColor.red.cgColor)
             context.cgContext.fill(CGRect(x: 0, y: 0, width: 1, height: 1))
         }
         let imageData = try XCTUnwrap(image.pngData())
-        let diskPath = pubkyImageDiskPath(for: uri)
+        let diskPath = pubkyImageDiskPath(for: uri, directory: directory)
 
         await cache.clear()
         cache.store(image, data: imageData, for: uri)
diff --git a/BitkitTests/PublicPaykitServiceTests.swift b/BitkitTests/PublicPaykitServiceTests.swift
index 8e664dec2..b8f8d8fcb 100644
--- a/BitkitTests/PublicPaykitServiceTests.swift
+++ b/BitkitTests/PublicPaykitServiceTests.swift
@@ -6,14 +6,12 @@ import XCTest
 final class PublicPaykitServiceTests: XCTestCase {
     override func setUp() {
         super.setUp()
+        // `clearPaykitDefaults()` removes seven live keys, including the bolt11 the app published to
+        // the user's homeserver along with its payment hash and expiry.
+        snapshotAppDefaultsDomain()
         clearPaykitDefaults()
     }
 
-    override func tearDown() {
-        clearPaykitDefaults()
-        super.tearDown()
-    }
-
     func testParseEndpointReadsSpecPayloadObject() {
         let endpoint = PublicPaykitService.parseEndpoint(
             methodId: "btc-lightning-bolt11",
diff --git a/BitkitTests/QuickPayPaymentCoordinatorTests.swift b/BitkitTests/QuickPayPaymentCoordinatorTests.swift
index d7ce35e65..3d08772f2 100644
--- a/BitkitTests/QuickPayPaymentCoordinatorTests.swift
+++ b/BitkitTests/QuickPayPaymentCoordinatorTests.swift
@@ -6,10 +6,6 @@ import XCTest
 @MainActor
 final class QuickPayPaymentCoordinatorTests: XCTestCase {
     private let settings = SettingsViewModel.shared
-    private var originalEnableQuickpay = false
-    private var originalQuickpayAmount: Double = 0
-    private var originalQuickpayDailyLimitMultiplier: Double = 0
-    private var originalCachedRates: Data?
     private var defaults: UserDefaults!
     private var suiteName: String!
     private var store: QuickPaySpendStore!
@@ -20,10 +16,20 @@ final class QuickPayPaymentCoordinatorTests: XCTestCase {
 
     override func setUp() {
         super.setUp()
-        originalEnableQuickpay = settings.enableQuickpay
-        originalQuickpayAmount = settings.quickpayAmount
-        originalQuickpayDailyLimitMultiplier = settings.quickpayDailyLimitMultiplier
-        originalCachedRates = UserDefaults.standard.data(forKey: "cached_fx_rates")
+        // Building a `CurrencyViewModel` syncs the display currency into the shared group.bitkit
+        // suite from its initializer, which the widget extension reads.
+        snapshotAppGroupDefaults("home_screen_display_currency_code_v1", "home_screen_display_currency_symbol_v1")
+        // Snapshot from disk rather than from `SettingsViewModel.shared`: its `@AppStorage` properties
+        // do not observe `setPersistentDomain`, so after an earlier suite's `resetToDefaults()` the
+        // singleton still reports the defaults, and writing those back in tearDown landed on top of
+        // the snapshot's restore.
+        snapshotAppDefaults(
+            "primaryDisplay",
+            "cached_fx_rates",
+            "enableQuickpay",
+            "quickpayAmount",
+            "quickpayDailyLimitMultiplier"
+        )
         suiteName = "QuickPayPaymentCoordinatorTests.\(UUID().uuidString)"
         defaults = UserDefaults(suiteName: suiteName)
         store = QuickPaySpendStore(defaults: defaults, dayKey: { "2026-08-15" })
@@ -38,14 +44,7 @@ final class QuickPayPaymentCoordinatorTests: XCTestCase {
     }
 
     override func tearDown() {
-        settings.enableQuickpay = originalEnableQuickpay
-        settings.quickpayAmount = originalQuickpayAmount
-        settings.quickpayDailyLimitMultiplier = originalQuickpayDailyLimitMultiplier
-        if let originalCachedRates {
-            UserDefaults.standard.set(originalCachedRates, forKey: "cached_fx_rates")
-        } else {
-            UserDefaults.standard.removeObject(forKey: "cached_fx_rates")
-        }
+        // No settings restored here: teardown blocks run first, so this would overwrite the restore.
         defaults.removePersistentDomain(forName: suiteName)
         defaults = nil
         store = nil
@@ -476,7 +475,7 @@ final class QuickPayPaymentCoordinatorTests: XCTestCase {
             app: appWithInvoice,
             wallet: WalletViewModel(),
             settings: settings,
-            currency: CurrencyViewModel(),
+            currency: CurrencyViewModel(currencyService: OfflineCurrencyService()),
             presentation: presentation(onRoute: { _ in }, onConfirm: {})
         )
         await fulfillment(of: [sendStarted], timeout: 2)
@@ -487,7 +486,7 @@ final class QuickPayPaymentCoordinatorTests: XCTestCase {
             app: appWithInvoice,
             wallet: WalletViewModel(),
             settings: settings,
-            currency: CurrencyViewModel(),
+            currency: CurrencyViewModel(currencyService: OfflineCurrencyService()),
             presentation: presentation(
                 onRoute: { _ in
                     if liveSendShouldNotEmit {
@@ -527,7 +526,7 @@ final class QuickPayPaymentCoordinatorTests: XCTestCase {
             app: appWithInvoice,
             wallet: WalletViewModel(),
             settings: settings,
-            currency: CurrencyViewModel(),
+            currency: CurrencyViewModel(currencyService: OfflineCurrencyService()),
             presentation: presentation(onRoute: { _ in }, onConfirm: {})
         )
         await fulfillment(of: [sendStarted], timeout: 2)
@@ -535,7 +534,7 @@ final class QuickPayPaymentCoordinatorTests: XCTestCase {
             app: appWithInvoice,
             wallet: WalletViewModel(),
             settings: settings,
-            currency: CurrencyViewModel(),
+            currency: CurrencyViewModel(currencyService: OfflineCurrencyService()),
             presentation: presentation(onRoute: { _ in XCTFail("Re-entry should not emit") }, onConfirm: {})
         )
         try await Task.sleep(nanoseconds: 150_000_000)
@@ -618,7 +617,7 @@ final class QuickPayPaymentCoordinatorTests: XCTestCase {
             app: appWithInvoice,
             wallet: WalletViewModel(),
             settings: settings,
-            currency: CurrencyViewModel(),
+            currency: CurrencyViewModel(currencyService: OfflineCurrencyService()),
             presentation: presentation(onRoute: { _ in }, onConfirm: {})
         )
         await fulfillment(of: [sendStarted], timeout: 2)
@@ -712,7 +711,7 @@ final class QuickPayPaymentCoordinatorTests: XCTestCase {
             app: appWithInvoice,
             wallet: WalletViewModel(),
             settings: settings,
-            currency: CurrencyViewModel(),
+            currency: CurrencyViewModel(currencyService: OfflineCurrencyService()),
             presentation: presentation(
                 onRoute: { _ in firstSettled.fulfill() },
                 onConfirm: { didConfirm = true }
@@ -724,7 +723,7 @@ final class QuickPayPaymentCoordinatorTests: XCTestCase {
             app: appWithInvoice,
             wallet: WalletViewModel(),
             settings: settings,
-            currency: CurrencyViewModel(),
+            currency: CurrencyViewModel(currencyService: OfflineCurrencyService()),
             presentation: presentation(
                 onRoute: { _ in XCTFail("Second pay should not emit a route") },
                 onConfirm: { didConfirm = true }
@@ -755,7 +754,7 @@ final class QuickPayPaymentCoordinatorTests: XCTestCase {
             app: appWithInvoice,
             wallet: wallet ?? WalletViewModel(),
             settings: settings,
-            currency: CurrencyViewModel(),
+            currency: CurrencyViewModel(currencyService: OfflineCurrencyService()),
             presentation: presentation(
                 onRoute: {
                     route = $0
diff --git a/BitkitTests/RNMigrationAddressTypeTests.swift b/BitkitTests/RNMigrationAddressTypeTests.swift
index e8fc26939..daf307e19 100644
--- a/BitkitTests/RNMigrationAddressTypeTests.swift
+++ b/BitkitTests/RNMigrationAddressTypeTests.swift
@@ -6,10 +6,11 @@ import XCTest
 final class RNMigrationAddressTypeTests: XCTestCase {
     private let migrations = MigrationsService.shared
 
-    override func tearDown() {
-        UserDefaults.standard.removeObject(forKey: "selectedAddressType")
-        UserDefaults.standard.removeObject(forKey: "addressTypesToMonitor")
-        super.tearDown()
+    override func setUp() {
+        super.setUp()
+        // `applyRNAddressTypeSettings` writes these for real; tearDown used to delete them outright
+        // rather than put back whatever the user had.
+        snapshotAppDefaults("selectedAddressType", "addressTypesToMonitor")
     }
 
     // MARK: - Helper Methods
diff --git a/BitkitTests/SamRockSetupRequestTests.swift b/BitkitTests/SamRockSetupRequestTests.swift
index 7a8f767b5..9e7343f87 100644
--- a/BitkitTests/SamRockSetupRequestTests.swift
+++ b/BitkitTests/SamRockSetupRequestTests.swift
@@ -286,6 +286,7 @@ private extension SamRockSetupRequestTests {
     }
 
     func prepareWalletKeychain() throws {
+        snapshotAppDefaults("selectedAddressType")
         try? Keychain.delete(key: .bip39Mnemonic(index: Self.testWalletIndex))
         try? Keychain.delete(key: .bip39Passphrase(index: Self.testWalletIndex))
         try Keychain.saveString(key: .bip39Mnemonic(index: Self.testWalletIndex), str: Self.testMnemonic)
diff --git a/BitkitTests/TransferServiceActivityTests.swift b/BitkitTests/TransferServiceActivityTests.swift
index f44fcc108..a0c810782 100644
--- a/BitkitTests/TransferServiceActivityTests.swift
+++ b/BitkitTests/TransferServiceActivityTests.swift
@@ -11,7 +11,11 @@ import XCTest
 /// App types are `Bitkit.`-qualified because some services are also compiled into the test target,
 /// so unqualified names would resolve to the duplicate and mismatch `Bitkit.TransferService`.
 final class TransferServiceActivityTests: XCTestCase {
-    private let testDbPath = NSTemporaryDirectory()
+    /// Unique per run: `NSTemporaryDirectory()` is shared with every other suite that calls
+    /// `initDb`, and `init_db` creates blocktank.db alongside activity.db, which none of them
+    /// cleaned up.
+    private let testDbPath = FileManager.default.temporaryDirectory
+        .appendingPathComponent("TransferServiceActivityTests-\(UUID().uuidString)", isDirectory: true).path
     private let activity = Bitkit.CoreService.shared.activity
     private var transferDefaults: UserDefaults!
 
@@ -19,16 +23,16 @@ final class TransferServiceActivityTests: XCTestCase {
         try await super.setUp()
         transferDefaults = try makeIsolatedDefaults()
         guardAppDefaults("transfers")
+        await drainCoreServiceQueue()
+        try FileManager.default.createDirectory(atPath: testDbPath, withIntermediateDirectories: true)
         _ = try initDb(basePath: testDbPath)
         try await Task.sleep(nanoseconds: 1_000_000_000)
     }
 
     override func tearDown() async throws {
         try await super.tearDown()
-        let dbPath = (testDbPath as NSString).appendingPathComponent("activity.db")
-        if FileManager.default.fileExists(atPath: dbPath) {
-            try FileManager.default.removeItem(atPath: dbPath)
-        }
+        await repointCoreToAppStorage()
+        try? FileManager.default.removeItem(atPath: testDbPath)
     }
 
     private func makeService() -> Bitkit.TransferService {
diff --git a/BitkitTests/UtxoSelectionTests.swift b/BitkitTests/UtxoSelectionTests.swift
index d228de813..76128e20e 100644
--- a/BitkitTests/UtxoSelectionTests.swift
+++ b/BitkitTests/UtxoSelectionTests.swift
@@ -4,13 +4,22 @@ import LDKNode
 import XCTest
 
 final class UtxoSelectionTests: XCTestCase {
-    let testDbPath = NSTemporaryDirectory()
     let walletIndex = 0
     let blocktank = CoreService.shared.blocktank
     let lightning = LightningService.shared
 
     override func setUp() async throws {
         try await super.setUp()
+        // `StartupHandler.createNewWallet` resets `selectedAddressType` and `addressTypesToMonitor` for a
+        // new wallet, and the running node persists address-search indexes. Teardown blocks run
+        // last-in, first-out, so the node stop registered below runs before this restore.
+        snapshotAppDefaultsDomain()
+        addTeardownBlock { [lightning] in
+            let isRunning = await MainActor.run { lightning.status?.isRunning == true }
+            if isRunning {
+                try? await lightning.stop()
+            }
+        }
         Logger.test("Starting UTXO selection test setup", context: "UtxoSelectionTests")
 
         // Wipe the keychain before starting tests
diff --git a/BitkitTests/WidgetsViewModelReorderTests.swift b/BitkitTests/WidgetsViewModelReorderTests.swift
index 50557ce26..ee4e1ecc8 100644
--- a/BitkitTests/WidgetsViewModelReorderTests.swift
+++ b/BitkitTests/WidgetsViewModelReorderTests.swift
@@ -7,14 +7,20 @@ import XCTest
 final class WidgetsViewModelReorderTests: XCTestCase {
     override func setUp() {
         super.setUp()
+        // `savedWidgets` is the user's home-screen layout; these tests delete it and persist
+        // a synthetic set over the top.
+        snapshotAppDefaults("savedWidgets")
+        // Saving a widget also mirrors its options into the shared group.bitkit suite, which the
+        // home-screen widget extension reads.
+        snapshotAppGroupDefaults(
+            "home_screen_news_widget_options_v1",
+            "home_screen_price_widget_options_v1",
+            "home_screen_blocks_widget_options_v1",
+            "home_screen_weather_widget_options_v1"
+        )
         UserDefaults.standard.removeObject(forKey: "savedWidgets")
     }
 
-    override func tearDown() {
-        UserDefaults.standard.removeObject(forKey: "savedWidgets")
-        super.tearDown()
-    }
-
     /// Builds a deterministic three-widget set regardless of the default install set.
     private func makeViewModel(order: [WidgetType] = [.price, .blocks, .news]) -> WidgetsViewModel {
         let widgets = WidgetsViewModel()
diff --git a/BitkitTests/WidgetsViewModelTests.swift b/BitkitTests/WidgetsViewModelTests.swift
index acf5fd235..c27bc2c41 100644
--- a/BitkitTests/WidgetsViewModelTests.swift
+++ b/BitkitTests/WidgetsViewModelTests.swift
@@ -5,14 +5,20 @@ import XCTest
 final class WidgetsViewModelTests: XCTestCase {
     override func setUp() {
         super.setUp()
+        // `savedWidgets` is the user's home-screen layout; these tests delete it and persist
+        // a synthetic set over the top.
+        snapshotAppDefaults("savedWidgets")
+        // Saving a widget also mirrors its options into the shared group.bitkit suite, which the
+        // home-screen widget extension reads.
+        snapshotAppGroupDefaults(
+            "home_screen_news_widget_options_v1",
+            "home_screen_price_widget_options_v1",
+            "home_screen_blocks_widget_options_v1",
+            "home_screen_weather_widget_options_v1"
+        )
         UserDefaults.standard.removeObject(forKey: "savedWidgets")
     }
 
-    override func tearDown() {
-        UserDefaults.standard.removeObject(forKey: "savedWidgets")
-        super.tearDown()
-    }
-
     func testSavingWidgetAfterEditingUnsavedOptionsDoesNotDuplicateAfterReload() {
         let widgets = WidgetsViewModel()
         widgets.deleteWidget(.suggestions)